1. Field of the Invention
The present invention relates to an information-processing apparatus that transmits information thereabout to a predetermined notification destination.
2. Description of the Related Art
Information-processing apparatuses can receive from an external apparatus a registration request to register the external apparatus as a notification destination of information about the information-processing apparatus, and transmit information thereabout to the registered notification destination (for example, Japanese Patent Laid-Open Nos. 11-203094 and 2000-137585).
After the information-processing apparatus has registered the external apparatus as a notification destination of information thereabout in response to the registration request transmitted from the external apparatus, the registered notification destination information is sometimes deleted when the information-processing apparatus is restarted. In this case, after the information-processing apparatus has been restarted, the information-processing apparatus transmits information indicating that it has been restarted to the external apparatus. Upon receiving the information indicating that the information-processing apparatus has been restarted, the external apparatus retransmits a registration request to the information-processing apparatus.
However, the information indicating that the information-processing apparatus has been restarted is not always received by the external apparatus. According to circumstances, the external apparatus may not be able to receive the information and retransmit a registration request. For example, if multicast transmission of the information indicating that the information-processing apparatus has been restarted is performed, the information is sometimes blocked by a router and is not received by an external apparatus existing on a network located beyond the router.
In such a case, the external apparatus incapable of receiving the information indicating that the information-processing apparatus has been restarted does not retransmit a registration request, because it determines that the previously transmitted registration request has already been received by the information-processing apparatus. In reality, the notification destination information registered in response to the previously transmitted registration request has been deleted. Accordingly, information about the information-processing apparatus will not be transmitted to the external apparatus. In order to prevent such a case, it is desirable that an external apparatus can retransmit a registration request at the right time.
If a period of time during which notification destination information remains registered (a valid period of registration of notification destination information) is fixed, all external apparatuses that need information about an information-processing apparatus transmit a registration request to the information-processing apparatus before the valid period expires. That is, both of an external apparatus incapable of receiving information indicating that the information-processing apparatus has been restarted and an external apparatus capable of receiving the information transmit a registration request before the valid period expires. However, in the case of the external apparatus capable of receiving the information indicating that the information-processing apparatus has been restarted, even though the external apparatus can receive the information, it must transmit a registration request before the valid period expires. Consequently, the number of transmissions of a registration request is increased.